naphthenic acid amides

ABSTRACT

A naphthenic acid amide having the formula: ##STR1## where R is the hydrocarbon portion of a naphthenic acid, 
     R 1  is H or Me 
     X is O or NH, and 
     n is a number having the value of 1-10. 
     The method of producing such amides is also disclosed.

INTRODUCTION

U.S. Pat. No. 4,589,979, which is incorporated herein by reference, discloses a method for neutralizing the organic acidity in heavy gas oils. The invention is described in this patent as follows:

"The invention comprises a method of neutralizing the organic acidity in heavy oils to produce a neutralization number less than 1.0 whereby they are rendered suitable as lube oil feed stocks which comprises treating said heavy gas oils with a neutralizing amount of monoethanolamine to form an amine salt with the organic acids and then heating the thus-neutralized heavy gas oil at a temperature and for a time sufficient to convert the amine salts to amides.

"The amount of monoethanolamine necessary to produce neutralization of a heavy gas oil which has a neutralization number greater than 1.0 can best be determined by using titration techniques or by trial and error.

"As indicated, after the amine has been added to the oil and salt formation occurs, the salts should be converted substantially to their amides. This can be done at temperatures about 25° F. greater than the boiling point of water for a period of time ranging over several days or higher temperatures can be employed and shorter reaction times used. Typically, if one were to heat the salt product at about 400°-500° F. for between 1-2 hours, the amide formation would take place."

The organic acidity present in the heavy gas oils are primarily naphthenic acids.

The present invention relates to the amides produced by the above described process as compositions of matter.

THE NAPHTHENIC ACIDS

Naphthenic acids are described in Kirk-Othmer's Encyclopedia of Chemical Technology, Third Edition, Volume 15, John Wiley & Sons, 1981, the disclosure of which is incorporated herein by reference.

The naphthenic acids obtained from petroleum and its distillates have hydrocarbon components corresponding generally to the hydrocarbon components of petroleum or its distillates from which they were derived. Preferred sources are the naphthenic acids found in gas oils, particularly heavy gas oils.

THE AMINES

The starting amines have the structural formula: ##STR2## where R₁ is H or Me,

X is chosen, at each occurrence, from O or NH, and

n is a small whole number of from 1-10.

In the above formula, when X is O, n is preferably 1. When X is NH, n is preferably 2 or more.

In addition to the structures defining the starting amines above, it is also understood that the formulas above also represent linear, branched and cyclic congenors of the structures mentioned above. For example, these starting amines may contain such compounds as aminoethyl piperazine, triethylene tetramine, diethylene triamine, and other structures which are branched or cyclic congenors of the above formulas. A preferred material is a commercially available compound or mixture of compounds which contain about 60 percent amino ethyl piperazine, about 25 weight percent triethylene tetramine, about 2 weight percent diethylene triamine, and about 12 weight percent of other admixtures of linear, branched and cyclic congenors of the above defined structures.

THE AMIDES

The amides of the invention have the formula: ##STR3## where R is the hydrocarbon portion of a naphthenic acid of the type previously described, and R₁, X, and n have the values previously described in Formula I.

Again, as above, the amides of the invention having the formula defined as Formula II, also are understood to contain multiple amide substitution where the amino compounds of the starting amines permit such a substitution. For example, diamides may be formed by reacting naphthenic acids with starting amines which have multiple free amino functional groups. These diamides would also be expected to have usefulness in performing the corrosion inhibition found to be important for these amides. These diamides are formed particularly when X is at least 1 NH group, whether or not X can also be more than 1 or X may also be represented by oxygen in higher molecular weight compounds.

In performing the steps described in U.S. Pat. No. 4,589,979, the amides of the invention are produced. During the formation of the amides a back pressure may be required. The amount of back pressure is related to the vapor pressure of the amine and may be determined by trial and error; however, at temperatures above 600° F., the back pressure required for formation of adequate effective amounts of our amide are predictably higher.

After the reaction is completed and the amides formed, they may potentially be separated from the petroleum or petroleum fraction by using conventional separation techniques such as solvent extraction which may employ either organic solvents or water. The most preferable method of extracting and isolating the amides comprises distillation, preferably vacuum distillation to separate the amides from the petroleum or the petroleum fraction.

A typical method for preparing the amides from a gas oil is set forth below:

A virgin gas oil was selected from a refinery located in the southern part of the United States. The neutralization number of this gas oil was 3.54. The neutralization number was determined using the well-known ASTM procedure D-974.

To determine the effectiveness of different amines at lowering the neutralization number, a weighed amount of the test vacuum gas oil and the additive were fluxed at between 450°-500° F. for 1.5 hours. This converted the salt formed by neutralization to the amide.

Using the above test procedure, the results are presented below in the Table.

                  TABLE I                                                          ______________________________________                                                                    Neutralization                                      Additive       Concentration                                                                              Number                                              ______________________________________                                         Blank          --          3.54                                                Polyamine*      1.43%      2.45                                                Bottoms                                                                        Polyamine       2.86%      1.90                                                Bottoms                                                                        Polyamine      6.0%        1.20                                                Bottoms                                                                        Tetraethylene**                                                                               2.0%        0.54                                                Pentamine                                                                      Tetraethylene  1.0%        0.82                                                Pentamine                                                                      Monoethanolamine                                                                              0.3%        1.63                                                Monoethanolamine                                                                               0.45%      1.22                                                Monoethanolamine                                                                              0.6%        0.82                                                ______________________________________                                          *A mixture of aliphatic and heterocyclic amines with boiling range betwee      410-465° F., Sp.G. ranging between 0.98-1.09 with multiple amine        substituents.                                                                  **A mixture containing: 65 weight percent of major isomers                     1. linear triethylene pentamine                                                2. linear tetra ethylene pentamine                                             3. amino ethyl tris  amino ethylamine                                          4. amino ethyl diamino ethyl piperazine                                        5. aminoethyl piperazino ethyl ethylene diamine                                6. piperazino ethyl diamino ethyl amine                                        7. bispiperazino ethyl amine, and 25 weight percent of the following majo      isomers:                                                                       (1) linear triethylene tetramine                                               (2) trisamino ethylamine                                                       (3) piperazino ethyl ethylene diamine                                          (4) bisaminoethyl piperazine, and about 10 weight percent of:                  1. pentaethylene hexamine                                                      2. other linear, branched, and cyclic congenors of similar amino               structures.                                                              

The gas oil containing the amide would then be vacuum distilled and the amide residue would be recovered. 

Having thus described our invention, we claim:
 1. A naphthenic acid amide having the formula: ##STR4## where R is the hydrocarbon portion of a naphthenic acid from a petroleum or a petroleum fraction,R₁ is H or Me X is chosen, at each occurrence, from O or NH, and n is a number having the value of 1-10.
 2. The naphthenic acid amide of claim 1 where X is O, n is 1, R₁ is H, and R is the hydrocarbon portion of a naphthenic acide from a heavy gas oil.
 3. The naphthenic acid amide of claim 1 where R₁ is H, X is NH, n is at least 2, and R is the hydrocarbon portion of a napthenic acid from a heavy gas oil. 